Segment Information Major Geographic Area (Details) - USD ($) $ in Millions	3 Months Ended								12 Months Ended
	Dec. 31, 2015	Sep. 30, 2015	Jun. 30, 2015	Mar. 31, 2015	Dec. 31, 2014	Sep. 30, 2014	Jun. 30, 2014	Mar. 31, 2014	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Revenues and Long-Lived Assets
Long-Lived Assets	$ 906.8				$ 899.8				$ 906.8	$ 899.8
Revenue	2,196.2	$ 1,865.5	$ 1,876.1	$ 1,676.0	2,207.1	$ 1,841.1	$ 1,851.4	$ 1,637.5	7,613.8	7,537.1	$ 7,122.3
Domestic
Revenues and Long-Lived Assets
Long-Lived Assets	600.1				572.9				600.1	572.9
Revenue									4,475.5	4,184.0	3,972.6
Total International
Revenues and Long-Lived Assets
Long-Lived Assets	306.7				326.9				306.7	326.9
Revenue									3,138.3	3,353.1	3,149.7
United Kingdom
Revenues and Long-Lived Assets
Long-Lived Assets	56.3				56.7				56.3	56.7
Revenue									687.7	688.3	568.3
Continental Europe
Revenues and Long-Lived Assets
Long-Lived Assets	58.6				66.4				58.6	66.4
Revenue									697.2	804.7	800.6
Asia Pacific
Revenues and Long-Lived Assets
Long-Lived Assets	108.8				102.2				108.8	102.2
Revenue									916.9	922.5	868.9
Latin America
Revenues and Long-Lived Assets
Long-Lived Assets	45.0				69.2				45.0	69.2
Revenue									383.5	470.4	464.5
Other
Revenues and Long-Lived Assets
Long-Lived Assets	$ 38.0				$ 32.4				38.0	32.4
Revenue									$ 453.0	$ 467.2	$ 447.4